Manufacture of burkeite



Sept. 22, 1931. H. w. MORSE MANUFACTURE OF BURKEITE Filed Maron so. 192s im.' heater Vin which the formation of scale is pre- Patented Sept. 22, 1931 HARRY WHEELER MORSE, or RE'Dwoon oirYfcALIFoRNIA MANFACTURE oF BURKEITE t Appncationlaiea Maron so; 1929. f. seiaim. 351,331.

This invention relates to the production of salts Vfrom brine, andl in particular to the recovery of solid sulfate-carbonate, of sodium from Searles Lake brine, ythe double salt being known as burkeite. i

It is an object of my invention to provide process whereby the aforesaid double salt can be continuously produced fronithe crude brine. 'f

Another object is to provide a process whereby the double salt will beproduced substantially free from admixed impurities, in particular, sodium chloride.- A

A further object is to provide a process wherein tails salts from a previous operation upon another portion of brine may be utilized. A further object is to provide a preheater of improved design for raisingthe brine t-o the desired temperature.

A still further object is to provide a prevented, and wherein foam is kept down.

Otherobjects will appear as the description proceeds.

In the following description, I shall refer in particular to that brine widely known as Searles Lake brine. A typical average analy sis of this crude material gives substantially the following figures Y Na2CO3 i- Na2SO4 6.65 NaCl 16.00 KCl 4.75

As is well known, the most valuable constituents ofthis brine are the potassium chloride andthe borax. These materials yare recovered by evaporating the brine to such a Borax (anhydrous basis) 740 point that the carbonate, sulfate andichlo'- ride of sodium crystallize out, whereupon the mother liquor containing the desired products is separated from the solids, usually called tails salts, and the mother liquor is thenk fur- ;gg ther evaporated t0 obtain the potassium "chloy process; and,

Per cent fide Aand the' bomV in Solid form. The. sans' f salts from this `process are frequently discarded as unmarketable, and will vhave 0an average analysis about as follows:

Per cent Na2CO3f 12.5 50 v:agso; 'r. i i\iac1- l 65.0

If raw SearlesLake brine is heated without evapora-tion to a temperature of 90-l00 C., with the addition of solidv sodium chloride, or of tails salts:as above, nearlyV pure sulfatecarbonate of sodaseparates in solidform. This `double salt may be advantageously used y innumerous processes which form no part of the present invention. Y If aweight of solid tails saltsI lequal to 6-10%fof the weight ofv brine treated isadded to the brine, and the mixture heated tol S90-T100o C. for a time, solid sulfate-carbonate-is produced in an amount equal to substantially 640% of the weight of thebrine. L Y In carrying out my invention, I- may use apparatus which I have illustrated in the accompanying drawings, in which:

. 70 `Figure l 1s a sideelevatlon, partly 1n sec'- tion, ofvlan apparatus adapted to carryoutimy Figure 2 is a side'elevationof another form of apparatus which may beemployed in a 5` modification of'vmy process.l

Referring now to Figure l, I have shownat l0V a preliminary mixer, in which the 'raw brineand tails salts are commingled. A pre# heater l2 is provided wherein the mixture is so heated, without substantial evaporation, until the double salt has separated. A. settler Mthen permits separationv of.` the sluge of crystals from most of the brine.A The crystal sludge then passes to a' filter 16 where the .5 i

double salt-isy sucked as dryv as practicable.

-Raw brineis fed into the mixer 10 through a feed pipe 18. Ahopper 20 permits the introduction of the solid tails salts. The two `are mixed as thoroughly as possible, by any .g

desired conventional mechanism, not shown in detail. Y

From the mixer, the raw material 1s fed n through pipe 22 into the L-shaped conduit 24.

One end of this conduit taps into the bottom of chamber of preheater 12; the other end feeds into a circulating pump 26, which discharges into a manifold 28. From this manifold, a number of vertical pipes extend upwardly and open into the chamber 25 of the preheater. A circulating system is thereby provided; liquid being drawn from chamber 25 by pumpr 26, through conduit 24, and discharged into manifold 28 and pipesBO, to be sprayed backlinto,the'chamber. A cylindrical casing 32 surrounds pipes 30, being closed above and below by tube sheets 34, through which the tubes extend. A steam inlet at 35'permits the rexternal heating of tubes 30, and consequently the heating of th'e'brine 'circulating through these pipes. The condensate outlet is indicated at 36.`

vrllhe preheater which I havel described above is, I have found, especially adapted for use in connection with processes of the type described herein.vr The small size and vertical arrangement of the tubes 30, couplediwith the rapid circulation'of the brinefand the suspended salts, completely prevents scaling or the formation of an insulating layer of solids on the walls of the tubes.

I have found further that I can prevent foaming by placing a baffleA 37 over the discharge ends of the tubes, in such a 'manner and of such a shape as to form a sheet of.

liquid extend-ing fromthe center ofthe vessel-to its wall. The ba e 37 has a surface similar to that formed by revolving a segment of a circle about one of its ends. As the liquid is driven upwardly by pump 26, it impinges against baffle 37, and issprea'd 'outwardly in a thin sheet which effectually breaks any ill foam which-may beginV to *form within the vessel.

A lead-od pipe 38' conducts the heated brine from the preheater 12 to the 'settling tank 14. Thissettler may be of any conventional design, and is not illustrated in detail. A draw-off line 40 isfprovid'ed for removing the liquor; While a return lin-e 42 may be provided, to send back and recirculate a partvof the clear liquid, if desired.4 Y f vThe salt which settles out in a sludgein hopper 44 flows into the receiver 46 of the filter. I-Iere it is taken up by suction, in a well known. manner, onto the surfaceV of 'drum 48. The filtrate is'led off through pipe 50. A spray 52 may be provided to wash ofi' the residual mother liquid; the wash water being, if desired, separately collected and led olf through pipe 54. The dried and washed crystals of sulfate-carbonate of soda are then scraped ofi' at 56, and may be collected as des sired'.

The tails salts from Searles Lake bri ne that has been treated as above, give the following typical average analysis:

Percent Na2CO3 NaZSOl 13.0 NaCl 75.0

It will be noted, by comparison with the figures given earlier, that a considerable amount of sodium carbonate and sulfate has been reclaimed, and the amount of sodium chloride relatively increased. I may use these tails salts in my mixer 10, or I may use those previously referred t0, as produced by the old process. rIhese latter are preferable, being higher in recoverable sodium carbonate and sodium sulfate.

In carrying out my process, brine is fed into mixer 10, and is there mixed with 6-10% its weight of tails salt, either from treated or untreated brine. The mixture is then fed into the preheater l2.A The rate of feed to the preheater is slow compared to the circulation maintained in the preheater by pump 26. A rapid circulation prevents overheating and scaling.` The feed is so proportioned that liquid will remain in the preheater about 15 minutes, and the steam is regulated to maintain a constant temperature of 90-100o C.

A constant feed of treated'sludge is maintained from preheater 12 to settler 14. The size of this settler is chosen so that a practically clear liquid can be drawn off at 40 and 42. Y

The thickened sludge is then passed to the filter, thedouble salt filtered ed, and, if desired, washed. Typical analyses of the unwashed and washed double salt follows:

Unwashen Percent Na2CO3 27.0 NagSO4 65.0 NaCl '7.0

y Washed Percent -Na2CO3 29.0 vNa2SO4 68.0 NaCl 2.0

The yield of the double salt, when the process is carried out as above is 610% of the weight of the brine treated.

In Figure 2 I have shown a slightly modified arrangement. The brine, instead of being led first to a mixer, is discharged directly into a preheater 12', the details of construction of which are the same as of the preheater 12 shown in Figure 1. From the pre'- heater, the brine is fed into an agitator 58, where tails salts are added through opening 60. The mixture then passes into-and through agitators 62 and 64, and is eventually discharged into settler 14. The clear liq- -ui'd is drawn off through pipe 40', and the sludge passes to filter 16.

While I have described specific embodiments of my process and apparatus, it is obvious that many changes could be devised by anyone skilled in the art. I desire to be limited, therefore, only by the prior artand the scope oi' the appended claims.

I claim:

l. A process for makingk sulfate-carbonate of soda which comprises heating together a liquid containing chloride, sulfate and carbonate of soda and a solid containing chloride, sulfate and carbonate of soda.

2. A process for making sulfate-carbonate of soda which comprises heating together, With agitation, a liquid containing chloride, sulfate and carbonate of soda and a solid containing chloride, sulfate, and carbonate of soda.

3. A process for making sulfate-carbonate bonate and chloride of soda, together with other salts,.comprising adding to said brine tails salts'from the evaporation of another portion of said brine, said other salts beingV substantially absent from said tails salts,V

taining chloride, sulfate and carbonate of soda.

4. A process or making sulfate-carbonate of soda which comprises adding to av brine containing sulfate, carbonate and chloride of sodium, tails salts from another portion of said brine, heating and agitating the mixture until the sulfate-carbonate separates, and separating the solid from the liquid.

5. A process for making sulfate-carbonate ot' soda from a brine having substantially the composition of Searles Lake brine, comprising adding to said brine tails salts from another portion of said brine, heating and agitating until the sulfate-carbonate of sodav separates, and removing the liquid from the crystals.

6. A process for making sulfate-carbonate of soda from a brine having `substantially the composition of Searles Lake brine, comprising adding to said brine a solid tails salt comprising sodium sulfate, carbonate and chloride, heating and agitating-,until the sulfate-carbonate of soda separates', and removing the liquid from the crystals. t

7 A process for making sulfate-carbonate of soda from a brine having substantially the composition of Searles Lake brine, comprising adding to said brine 610% of its Weight of a solid tails salt comprising sodium sulfate, carbonate and chloride, heating and agitating until the sulfate-carbonate of soda,

separates, and removing theliquid from the crystals.

8. A process for making sulfate-carbonate of soda from a brine having substantially the composition of Searles Lake brine comprising adding to said brine 6-10% of its Weight of a solid tails salt comprising sodium sulfate, carbonate and chloride, heating to 90-100o C. until the sulfate-carbonate of soda separates, and removing the liquid.

9. A process for making `sulfate-carbonate of soda from a brine containing sulfate, carisc 

